DE 10 2010 037 582 A1 discloses a method for determining a spatial arrangement of photovoltaic module groups, i.e. of individual photovoltaic generators, of a photovoltaic installation. A sequence of measurement values of a radiation-dependent electrical characteristic variable of the individual photovoltaic module groups, for example the power generated by them, is measured while the photovoltaic installation is exposed to light irradiation with a temporally and spatially varying irradiation intensity owing to drifting clouds. The relative spatial arrangement of the photovoltaic module groups with respect to one another is determined from time shifts between the sequences of measurement values in the case of the different photovoltaic module groups. In this case, weather data, in particular wind speed and wind direction, can be taken into account, which can be ascertained from the image data of a camera. In addition, the extent of the photovoltaic module groups can be determined. The extent of the photovoltaic module groups directly influences the width of a fall and/or rise in the detected electrical characteristic variable, such that statements about the lateral extent of the module groups in the respective cloud drifting direction are possible from an analysis of these transition widths. If a plurality of drifting directions is taken into account, information about the shape and area extent of the photovoltaic module groups considered is obtained in this way.
DE 10 2011 056 207 A1 discloses a method for localizing stationary objects which bring about temporary shadings of light-sensitive components of a photovoltaic installation with a sun shadow. At least one electrical signal from the light-sensitive components is analyzed with regard to the occurrence of shading brought about by a stationary object. The direction of the object bringing about the shading is deduced from the positions of the sun when the shading occurs. In addition, the at least one electrical signal is analyzed with regard to the migration of the sun shadow of the object over the light-sensitive components with the changing position of the sun and the distance of the object bringing about the shading is deduced therefrom. The light-sensitive components can be solar cells, solar modules composed of solar cells, strings composed of solar modules or additionally provided sunlight sensors of the photovoltaic installation. The electrical signal can be the electrical power of the light-sensitive components. From the electrical signal it is also possible to deduce whether the changes thereof with the changing position of the sun indicate shading brought about by a non-stationary object. Such shading is not present if the direction in which the sun shadow moves across the light-sensitive components of the photovoltaic installation is not opposite to the change in the position of the sun. The speed at which the sun shadow moves across the light-sensitive components of the photovoltaic installation also matches shading by a stationary object only within specific limits. Conversely, fast migration of a sun shadow over the light-sensitive components of a photovoltaic installation indicates a shading obstacle travelling past or flying past. The analyzed electrical signal can originate from a single light-sensitive component of the photovoltaic installation with an extent in the direction of the migration of the sun shadow. The signal changes as soon as the leading shadow edge of the sun shadow reaches the light-sensitive component. This change continues until the light-sensitive component is maximally shaded by the respective shading obstacle. A change in the electrical signal in the opposite direction commences when the sun shadow increasingly releases the respective light-sensitive component again, which begins as soon as its trailing shadow edge reaches the light-sensitive component.
US 2010/0204844 A1 discloses a method for controlling a system for generating electrical power. In that case, a power source affected by geographically progressing states, e.g. weather states, is monitored in order to detect changes in its power output. Characteristics of the observed changes are analyzed in order to ascertain whether the changes are caused by a geographically progressing state that might influence other power sources in the vicinity. This information is used to extrapolate imminent power output changes for the same and other power sources. The extrapolations enable the power generating system to maintain the total power output within operating requirements. For example clouds passing over a photovoltaic array cause fluctuations in the power output if they shade the individual panels. If the power generated by the individual panels or sub-arrays at known locations is tracked over time, the speed and direction of the temporary shading fluctuations can be calculated. If the speed and direction are known, calculations can predict which other arrays will be affected in the same way and at which time.
In computed tomography, absorption profiles of an object are determined from different directions and a volume structure of the object is reconstructed from the absorption profiles. The reconstruction is based on the fact that the total absorption occurring along each path through the object is the integral of the specific absorption or absorption density along the path through the object. If total absorptions for different, intersecting paths are present, the local absorption density can be calculated therefrom. For evaluation of absorption profiles by computed tomography, various algorithms in the form of commercial programmes are available which determine the volume structure of the respective object from absorption profiles recorded in a comparatively small number of different directions, and do so robustly with respect to displacements of the object that occur during the recording of the absorption profiles.